Iron Uptake

[kaaikop]

Hello guys! I am still trying to evaluate what's going on in my tank right now (long story...), so still doing tests daily to try and evaluate uptake rates for the different ferts.

Here what I find weird: I dose 100ml of CSM+B containing Fe (mix is 2 tbs. in 500ml), that raise Fe about 0.7 ppm. The next morning it's all GONE!
I have recently added a little bulkhead for circulation (runs all day along with CO2 injection) and an airpump which runs now 24h.
Phosphates are also being depleted very fast.

Even weirder, I dont have to dose NO3 anymore (actually going up, acc. to my shitty test kit). What in the world is going on?

BTW great forum! i just subscribed few days ago (should get the money whenever Paypal decides so...)

 

[Tom Barr]

I think you have seen a major issue when addressing testing Fe.

Seldom do they give you a time after dosing, there is no standard method in other words, for the measure of Fe in the tank water.

There are other issues as well:

1. Type of chelator makes a large difference in what is measurable in the tank's water.
2. The tank's KH makes a large issue(harder waters tend to require more, especially if the chelator is poorly suited in #1).
3. How much of a dose, which is typically defined as concentration x Exposure, the actual plant gets to the leaves.
4. Rate of growth(slower growth rates, say with a tank w 1.5w/gal+ CO2 vs 4.5 w/gal w/CO2)
5. Substrate sources
6. Test is use for a proxy for all trace metals, other trace metal may or may not be limiting, an issue etc.
7. Antagonistic effects of two or more of the above.

That's just what I think of off the top of my head.

Fe test kits for the water column are a very poor indicator/correlator of plant health, algae and dosing routine needs.

I'd not bother.
I'd suggest optimalization of the NO3, PO4, K, CO2, GH, then add small amounts progressively more till no improvement in plant health is noted.

This is how many crops are evaluated, but they use treatment dry weights vs the control weights to measure relative growth rates, something seldom if ever done by hobbyists.

Another analysis done in conjunction is to use actual tissue concentration as well as RGR's(relative growth rates) for comparison. Note luxury uptake of metals is wide spread and does not reflect demand that will influence growth rates, just merely uptake.

What can occur under a non steady supply: the luxury excess uptake is utilized in leaner times. As long as the lean peroid does not limit growth, we are okay.
In general, one would always have a good steady supply in excess of demand for growth from a source to prevent issues with plant metabolism.

NO3 is used like this in a daily diurnal cycle. Typically NH4 is used all day till too low/gone, then the plant uses the storage of NO3 from the large central vacuole, at night the vacuole is replenished etc depending on the plant species.

I'm not sure why you run the air pump all day/night though.



Regards,
Tom Barr

 

[Tom Barr]

Also, since you feel compelled to test and measure PO4/NO3/Fe, why not actyually know what you are testing?

Make some reference standards to evaluate your test kits, since you still think that they are correct and warrant you to change your dosing routine which can affect plant growth. Test kits, especially cheap ones are poor in their accuracy, that's why the charge more to the more expensive Lamott, Hach etc.

Many aquarist use the the argument: "well my test kits are good enough for me"
I have never bought that argument. First, how do they know? "My plants look good"

Hummm.............so are they using the test kit or using the plants as a test kit?

These same aquarists also seldom if ever calibrate their test kits and those that do, do so with only one, not 2 or more points in the range they are sampling.

To be sure, and sure enough to alter any dosing routine, one must calibrate their test kit. Brands that where fine and accurate once, are not always going to be the next time, shelf life of reagents, how long the vendor has had them on their shelf, not cleaning things/vials etc well etc.

You might get a good level of confidence with the cheaper test kits, but you still should do this process.

Also, test weekly, or between doses, every few days rather than daily.
This way you will larger changes and these are more detectable, especially with poorer inaccurate, low precision test/methods.

This is hard sell for hobbyists, but one that needs to be done and considered very
seriously if they take this route.

I tend to suggest EI for this reason and most folks stop testing afterwards anyway. It takes the focus away from test kits etc and focuses things more on CO2 and plants.

If you want to obsess about testing, obsess about measuring CO2, at various time points throughout the day cycle and do so often.

You will get more out of that, and with a KH reference pH probe or drop checker, this is pretty easy.


Regards,
Tom Barr

 

[kaaikop]

Thanks for the reply.

This tank is recuperating, after losing a battle against BBA, so I guess there are a lot of things I am trying to get right all at once, but I do seem to be on the right track. Basically I had given up on this tank, after the appearance of BBA, I went back to low-light, non-CO2, etc, then it went downhill from there on... So I am back at it, and trying to get better advise this time around, and changing little things (like reducing photoperiod for example), increased CO2, increased dosing until I can actually "measure" some in my tank, but I am on a learning curve here.
That's the only reason i test, is I want to undertand what's going on.
I still have issue (water is constantly 'milky', there are still some BBA
appearing on the leaves of some plants after a few days, so I am far from where I want to be, but definately getting better.

Here are a few specs of the tank:

-150g (72x27x18), 2 x Eheim 2128 filters, Pres. CO2 through twin Aquamedic 1000 reactors, 4 x 96W CF, 2 x 30W, 4 x 21W T5.
KH is 50ppm (have to add baking soda every 2 weeks to keep it up there), temp. 25C, etc.

Here is what the tank looks like right now: tank120307.jpg - Image - Photobucket - Video and Image Hosting

 

[VaughnH]

Plants are largely made of carbon, and the carbon comes from CO2, so CO2 has to be the single most important nutrient to get right. You can buy a "drop checker" (CO2 indicator) made by Red Sea for about $12 to $14 at a LFS, or make one for much less, use 4dKH DI or distilled water in it, and thus know that you have 30 or so ppm of CO2 in the water. I can't see a reason not to do that. Then, if you just follow the EI dosing recommendations, perhaps modified according to what you see the plans doing, you will have all of the nutrients nailed down. And, you will not have used a single test kit.

 

[kaaikop]

Well, I still dont fully understand how this "drop checker" can work so accurately, but I will give it a try (only way to learn right?).
I do realize the limitations of the KH/pH equation, because in my tank, based on my testkits and pH meter, my CO2 would range from 27 to 53ppm of CO2, yet the fish are all doing fine, which goes to say...

 

[Tom Barr]

You can at least measure the KH standard and the tank's KH and see how far off the test kit is vs the actual.

The Drop checker is simple, add the same amounts of water(the KH reference solution) + test agent(narrow range pH indicator solution) into the drop checker.

Add that to the tank so there's an air gap between the test solution and the tank's water.

Wait about 2 hours for good color.
Dail in the CO2 accordingly.

You need to have a good mix of CO2 in the tank and good flow, you might be a little low on flow.

You have enough light/CO2 reactor etc.

So the rest is up to you.
Measure and adjust that CO2.

If you use a pH meter, you may use the membrane method or use the pH reading as a relative measure against the known inside the drop checker.

Regards,
Tom Barr

 

[kaaikop]

Another question: is the Iron found in CSM+B is sufficient, or do we have to add some on top of it?

 

[dzaninov]

Do you have a UV sterilizer ? The only time my Iron disappeared overnight was when I was running a UV sterilizer. Is the test kit that you are using able to detect chelated Iron ? I use Hagen Iron test kit and it is very accurate with CSM and will show results in less than 30 minutes.

 

[Tom Barr]

It should be fine, I have preferences with traces and CMS is not one of them, it's cheap, but I know the trace I have coming up this summer will be about as plant tank specific as we can get.

Regards,
Tom Barr

 

[Steve Hampton]

It should be fine, I have preferences with traces and CMS is not one of them, it's cheap, but I know the trace I have coming up this summer will be about as plant tank specific as we can get.

Regards,
Tom Barr

That is super good news. My supply of TMG will run out in about 3 months, I have a pound of CMS+B that can tide me over until the BarrTraces is available. I love TMG and have never liked CMS as much. I'm excited to give your stuff a try.

 

[BHornsey]

It should be fine, I have preferences with traces and CMS is not one of them, it's cheap, but I know the trace I have coming up this summer will be about as plant tank specific as we can get.

Regards,
Tom Barr

Tom,

Any confirmation of UK availability yet?